A dispensing pump of this type has been known from, e.g., West German Utility Model No. DE-Gbm 88,00,880.0. The partition of the upper housing part, which is telescopingly guided in the lower housing part, is provided there with a pipe socket, which is directed in the downward direction toward the partition and the suction valve, and is surrounded by a reinforced annular shoulder of the bellows. This pipe socket is provided on its top side with a conical valve seat annular surface, on which a closing member is elastically seated, and the said closing member is elastically supported at the closing front wall of the upper, two-part housing part, and is movably guided in the pipe socket by means of an axial cross rib. The upper housing part consists of two hollow bodies, which are lockingly connected to one another, and one of which has a cylindrical guide wall, with which it is axially movably guided in the lower housing part between two end positions. The second hollow body of the upper housing part, which is lockingly inserted into a projecting cylindrical wall section above the partition, has an eccentric, channel-like discharge opening, which extends axially parallel and is in direct connection with a hollow space, in which the closing member of the discharge valve is arranged, and which is also connected, via this discharge valve, to the interior of the bellows, while the upper housing part as a whole moves in relation to the lower housing part, performing a delivery stroke in the downward direction.
Even though it is possible, in principle, in this type of dispensing pump (to which also corresponds, e.g., the dispensing pump according to EP-A-0,194,417, and which have a bellows as a pumping member), to draw in two or more different media simultaneously from separate containers, the mixing of these media is uncontrollable, because all the media drawn in simultaneously flow through the same pump chamber.
A paste dispenser has also been known (U.S. Pat. No. 4,438,781), but it has no bellows as the pumping member, but two pump plungers, which can be actuated manually and draw two media simultaneously, in cooperation with suction valves, from two paste containers, which are located concentrically one in the other, but are separated from each other, and are provided with a follower plunger each, and deliver them via separate channels into a storage space, which is arranged directly in front of a discharge opening. This storage space surrounds a plunger-like closing member, which is arranged at an elastic diaphragm wall, to which the delivery pressure of the medium is admitted.
The two pump plungers are arranged coaxially to one another, are rigidly connected to one another, and are provided with a common actuating member, which is actuated manually. To pump different amounts, the pump plungers have different diameters. The likewise coaxial, cylindrical pump chambers, which communicate with the separate paste containers via suction valves, are connected via separate discharge valves to two separate guide channels, which, extending approximately axially parallel, are arranged eccentrically to the pump chambers, and open into the storage space.
This leads to a labyrinth-like shape of the space of the pump chambers connected to each other and of the guide channels, which is difficult and expensive to prepare, so that it is unsuitable for mass production, especially in the case of a so-called disposable article.